You can screen, keep them out of your building. But up to the screening point, you're vulnerable. -Security expert Kevin Mattingly

Editor's note: This is the third part in a four-part series focused on ballpark security following the recent Boston Marathon bombings. These stories are meant to inform readers on the mechanisms in place to keep ballparks safe and how different threats can be addressed. They are not intended to raise alarm about or discourage fans from attending baseball games or other sporting events.

BOSTON — Security experts, Boston Red Sox and MLB officials all believe baseball games to be safe. Within the examination of what potential threats do exist for stadiums, however, the consensus among industry experts is that handheld weapons — guns, knives — are more of a realistic threat than a bomb.

A pressure-cooker bomb would be very tough to sneak by a metal detector — but, in the wake of the Boston Marathon bombings, improvised explosive devices are on the public's mind.

"I think an IED would be virtually impossible to sneak into the building," said Steve Adelman, a Phoenix-based lawyer specializing in venue security. "Because it's got to have something that's metal that's going to set off, even a relatively casual wanting with a magnetometer. … My general comment is, people tend to focus on the thing that just happened. There's the natural inclination to try to refight the last battle. And so, people are thinking about IEDs."

Kevin Mattingly, a deputy director of operations for the Phoenix Convention Center and a former cop, agreed that the chances of sneaking in an explosive — something that in all likelihood has some sort of metallic component — are "pretty nil."

"It's true that a knife, a gun, an act of violence in a sporting venue is more probable," Mattingly said. "I think acts of violence occur at pretty much every major sporting event. Seems like you can't go to anything without somebody getting arrested, somebody punching somebody… (but) If somebody has asked the question two weeks ago, what's the likelihood of a bomb going off at the Boston Marathon, I'm sure most people would have rolled their eyes and said, 'Gee, why the Boston Marathon? There's so many juicier targets around.'"

In terms of possible explosives, the most dangerous place at a sporting event — or at any public gathering with a security checkpoint — is likely the area before one reaches the checkpoint.

"You don't have to strike in the ballpark to affect the ballgame," Mattingly said. "I've been to Fenway. You get off the T, you walk down the street. Parked cars and street vendors and heck, the street vendor carts, many of them have propane bottles strapped to them to keep the hot dogs warm.

"So you design your buildings to keep explosive objects away," Mattingly continued, "especially automobiles and those sort of things. Or you make arrangements by closing streets on game day or closing sidewalks on game day to create the standoff that you need. But you're always going to be vulnerable to the man-carried device, at least outside your building. You can screen, keep them out of your building. But up to the screening point, you're vulnerable. And we all are. That's not just stadiums. You name the business: the courthouse, the post office, police station. Up to the screening point, you're vulnerable."

Sam Kennedy, the Red Sox chief operating officer, said flatly that Fenway Park is safe, and that the team has been "very vigilant" with vehicles around the perimeter.

The inside of the ballpark, Adelman reinforced, is not an easy place to bring a bomb.

"Nobody's going to sneak in a bomb," said Steve Adelman, a Phoenix based-lawyer who specializes in venue security. "They could easily enough sneak in a weapon. So if you're talking about the threat of an active shooter inside Fenway Park, yeah, that's probably a realistic possibility just as it is at most other stadiums."

Experts agree that all professional sports leagues take security seriously. But guns and knives are typically smaller than an improvised explosive device or IED. Knives don't have to be metallic.

The Red Sox for now require all fans entering Fenway Park to be checked security personnel with a handheld metal-detector — that they're wanded. Before the Marathon bombings, wanding was random at Fenway. The team is going to review its security procedures after this homestand.

MLB mandates bag checks — although it's important to note that the sizes and methods vary by club. What's allowed in each ballpark can be different, and how they check bags can be different.

The Red Sox altered the manner in which they checked bags after the bombings, two sources familiar with Red Sox security operations told MassLive.com. But wanding isn't mandatory across MLB.

"To the best of my knowledge, baseball stadiums don't generally wand people, and you know what the wand is, it's a magnetometer — what normal people call a metal detector," Adelman said. "So the magnetometer is good if what you're trying to do is find traditional guns or knives. they'll detect metal objects. If you have something that's aluminum, it may or may not show up."

Mattingly said "there's way too much stuff that can get through a magnetometer."

"You're not going to catch (non-metallic knives)," he said. "You're going to get a lot of false readings because these stadiums weren't built for magnetometers and that means there's rebar in the floor."

Adelman points out that it's almost impossible to stop the first bullet, at ballparks and generally.

In a presentation Adelman gives, he shows a slide of a fan running on the field next to Barry Bonds. That's not a unique incident — sometimes, when a fan runs on the field, they are able to reach a player before being apprehended. If that fan had malice, well…

"The protection for the players is really good with in the confines of — they're out in the open," Adelman said.

But it's not just players who are endangered in those settings: guns and knives in the stands would endanger fellow fans.

How are guns and knives guarded against, then?

Security personnel on the field have to be watching the fans and not the game. Mattingly has seen sideline security workers more than once looking at the action instead of the fans. It's important, too, that security personnel who potentially have to chase someone be in athletic shape.

"It's a bit of a pet peeve of mine," Adelman said. "I work with a bunch of security companies, there are two related issues here. One is the optics of it, the other is just basic security. The optics of it is, if you got big, fat, slow guys who are your field-level security, that's a bad look. It doesn't look like you're able to secure the field. More importantly, you want to have people at field level who are physically fit enough so that somebody who pierces the barrier of fan vs. player can quickly be apprehended before they get to Will Middlebrooks."

Short of pat downs for every fan, ensuring handheld weapons do not enter a ballpark is difficult, Adelman said. MLB does not mandate pat downs, while the NFL does. The Red Sox conduct them randomly.

Venues have their own gun policies. In certain states, it's legal to carry guns publicly. "At that point, people are kind of on the honor system unless the club has its security people doing pat downs," Adelman explained.

"One man's opinion, look — I'm a security professional," Adelman said. "I never mind if someone wants to pat me down because for that brief moment of inconvenience. I know that everyone else is getting patted down too. And I'm good with that. I'm one of those people that doesn't complain about (the Transportation Security Administration), because no planes have crashed and been hijacked since TSA started. Maybe there's cause and effect, and maybe there's not, but I certainly like that there have been no hijackings since 9/11."

An old adage may stand true for this subject, however: "if there's a bad guy who's really intent on doing harm," Adelman said, "it's very difficult to stop them."